The present invention relates to objects within computer systems and the reflection of their relevance during their lifetime.
More and more storage of computer systems is filled up with data objects (an object according to the current terminology refers to any kind of related data treated as a unit) for which nobody can judge their relevance. In many cases it is completely unclear whether these objects can be migrated to some sort of external storage or even if these objects may be deleted. The increasing flood of data available through the Internet is even escalating the problem of judging the relevance of objects. All types of storage are affected by this problem: files within file systems, entries within databases, entries within caches and so forth.
Storage within computer systems is frequently filled with data for which one knows that it changes its relevance over time, independently of being used or not, but the aging characteristics are unclear in general and in specific with respect to a certain data object. Aging characteristic, according this description, is understood as the characteristic behavior of increase and decrease of an object""s relevance during its lifetime. Since the maintainer of the storage, being either a person or some software that maintains the storage, is frequently oblivious to the relevance properties of the data that is stored, removal decisions are made on the basis of various heuristics and assumptions.
One state of the art approach in this area is to use a timestamp, for instance the creation time or the last modification time of an object, as an indication of relevance. This is a rather unsatisfactory approached as the creation time is not connected to the importance of an object. Moreover, knowing the last modification time of and object does not allow to deduce its importance in the future. Any kind of timestamp gives no indication whether the relevance of an object will increase or decrease in the future. Finally such approaches have the disadvantage of trying to deduce relevance from an organizational parameter of the storage system and not from the data itself
Another state of the art approach can be found within cache systems being used for instance as second or first level caches for processors. Objects in such environments are tagged with a reference count indicating the access frequency during a previous time interval. The same disadvantages as discussed above do apply to this case as well. Even if a reference count would reflect some indication of relevance, this would represent a relevance indication relating to the past and not to the future. As further disadvantage access to the data, comprised within the object, and inspection of this data is involved.
The invention is based on the objective to propose a flexible and improved mechanism for estimating the relevance of objects stored within all types of computer storage.
The objectives of the invention are solved by the independent claims. Further advantageous arrangements and embodiments of the invention are set forth in the respective subclaims.
The invention relates to objects within a computer-system. Said objects comprise object data and the invention relates to a specification of an object-specific, self-reflecting relevance-function associated with the objects. The specification of the relevance-function allows an object-exploiter to evaluate an object-relevance at a certain point in time without inspecting the object-data.
Due to the current invention it has become possible that already the object creator/provider can incorporate his knowledge of the data relevance into the object. It also has become possible to model the future variation of an object""s relevance and importance; gradual changes over time of the relevance of an object can be modeled. It is not necessary to access and interpret the object""s data to estimate its relevance; thus time consuming data accesses to unimportant data can be avoided completely. As relevance functions allow to model the future relevance and importance of an object, new pro-active replacement strategies for these objects, stored within some physical storage, became possible.